WDPN33 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.9N 156.1E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 153 NM NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A TIGHTLY
WRAPPED TYPHOON (TY) WITH A RAGGED EYE FEATURE THAT HAS DEVELOPED
OVER THE LAST SIX HOURS. TY 25W HAS RAPIDLY INTENSIFIED IN A HIGHLY
FAVORABLY ENVIRONMENT OVER THE LAST 24 HOURS AND IS NOW ASSESSED TO
BE 85KTS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON A 200753Z F-17 SSMIS 37GHZ MICROWAVE IMAGE REVEALING SYMMETRIC
BANDING WRAPPING AROUND A LOW-LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY AND OBJECTIVE FIXES LISTED BELOW. IT IS NOTABLE
THAT TY 25W IS CONSIDERED SMALL IN SIZE AND THE CONVECTIVE FIELD IS
CURRENTLY MEASURED AT 220NM, SO THE DVORAK METHOD IS PRONE TO
UNDERESTIMATING INTENSITY. AS A RESULT, THE INTENSITY ASSESSMENT
LEANS ON THE HIGHER END, CLOSER TO SATCON AND DPRINT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGES TO THE EAST AND WEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 84 KTS AT 200248Z
   CIMSS ADT: 59 KTS AT 200530Z
   CIMSS AIDT: 72 KTS AT 200530Z
   CIMSS D-MINT: 83 KTS AT 200248Z
   CIMSS D-PRINT: 99 KTS AT 200700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 25W WILL CONTINUE NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE OVER THE NEXT 24
HOURS AS THE STEERING ENVIRONMENT BECOMES INCREASINGLY COMPLEX. A
SEPARATE SUBTROPICAL RIDGE OVER SOUTHERN JAPAN IS EXPECTED TO
BUILD, CAUSING TY 25W TO SLOW AND CURVE ERRATICALLY AROUND THE
PRIMARY RIDGE TO THE EAST FROM TAU 36-48. THE CURRENT FORECAST
REFLECTS A WEAKENING IN THE RIDGE AFTER A DEEP-LAYER MAJOR
SHORTWAVE TROUGH BREAKS DOWN THE RIDGE OVER JAPAN, ALLOWING TY 25W
TO TRACK NORTHEASTWARD, EVENTUALLY BECOMING EMBEDDED IN AN
UPPER-LEVEL TROUGH AND BEGINNING EXTRATROPICAL TRANSITION AT TAU
96. 
THE ENVIRONMENT WILL BE FAVORABLE OVER THE NEXT 48 HOURS FOR
INTENSIFICATION WHILE IN WARM SEA SURFACE TEMPERATURES, LOW
VERTICAL WIND SHEAR, AND STRONG UPPER-LEVEL DIVERGENCE. AFTER TAU
48, VERTICAL WIND SHEAR WILL INCREASE UNFAVORABLY DUE TO THE
APPROACHING TROUGH, CAUSING WEAKENING THROUGHOUT THE REMAINDER OF
THE FORECAST PERIOD. EXTRATROPICAL TRANSITION WILL START AT TAU 96
AND CONTINUE THROUGH TAU 120.


MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS NOT IN AGREEMENT
THAT TY 25W WILL CURVE NORTHEASTWARD AS REFLECTED IN THE FORECAST.
THERE IS A BIFURCATION SCENARIO WITHIN THE JTWC MULTI-MODEL
CONSENSUS CENTERED AROUND THE QUASI-STATIONARY PERIOD AT TAU 48-72
AND THE BREAKDOWN OF THE RIDGE TO THE WEST. GIVEN THAT THERE IS 
SIGNIFICANT UNCERTAINTY IN THE TRACK GUIDANCE, AND 
THAT THE DEEP-LAYER TROUGH MAY NOT BREAK DOWN THE RIDGE OVER
JAPAN, THE TRACK AND INTENSITY FORECAST MAY DEVIATE FROM THE
CURRENT FORECAST GREATLY DUE TO A LONGER QUASI-STATIONARY PERIOD.
THE INTENSITY GUIDANCE IS IN BETTER AGREEMENT, BUT AS MENTIONED, IS
ENTIRELY DEPENDENT ON THE TRACK GUIDANCE ABOVE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
NNNN